20 (R)-Ginsenoside Rg3 is a tetracyclic triterpenoid ginsenoside saponin monomer isolated from Red ginseng (Red ginseng is a cooked products of Panax ginseng C. A. Mey). It is isolated from Korean ginseng by the Japanese scholar Kitagawa Hoon in 1980, and its molecular formula is C42H72O13, the relative molecular weight of 784.3. 20(R)-Ginsenoside Rg3 has the efficacy of synergistic detoxification, improving the symptoms of qi deficiency, enhancing the immunity of human bodies and so on. In addition, studies have shown that ginsenoside Rg3 still has the role of inhibition of tumor cell proliferation, infiltration and metastasis, can induce apoptosis of liver cancer cells, prostate cancer cells, leukemia cells, cervical cancer cells.

Because of its large molecular structure, 20 (R)-ginsenoside Rg3 is not soluble in water and other high polarity solvents, but also not soluble in petroleum ether, chloroform and other low polarity or non-polar solvent; 20 (R)-ginsenoside Rg3 easily soluble in pyridine, ethanol solution (50%˜70%), strong acid aqueous solutions (pH<2) and strong alkaline solutions (pH>10). It belongs to the Class IV drugs of Biopharmaceutics Classification System (BCS), and owing to small solubility and transmembrane permeability and low bioavailability, the pharmacological actions of 20(R)-ginsenoside Rg3 are restricted.
In recent years, many scholars have conducted in-depth researches on the polyacylation of natural products, for example, Liu Jikai et al. have synthesized the bergenin pentaacetylate by solid acid catalysis, as shown in the Patent Application which Patent Application number is CN200510010970.0 (Kunming Institute of Botany, Chinese Academy of Sciences). Compared with the raw material bergenin, the animal experiments showed that bergenin pentaacetylate has obvious synergistic pharmacological effect, and can effectively overcome the shortcomings of bergenin, such as poor antitussive and antiasthmatic effect and poor oral absorption.
Mangiferin pentaacetylate, mangiferin heptanoyl, and mangiferin hexaobutyanoyl compounds have been synthesized using catalyst sulfuric acid by Deng Jia Gang research group in Guangxi University of Medical Sciences. (Experiment Traditional Medical Formulae Vol 18, No 24, page 185-189); The pharmacological experiments of mangiferin pentaacetylate, mangiferin propionyl heptaacetylate and mangiferin butyryl hexaacrylate, developed by catalytic synthesis with sulfuric acid (the research group of Deng Jiagang et al., Guangxi Medical University) showed that these three mangiferin derivatives can provide similar pharmacological action as mangiferin, with the dosing of ¼ of mangiferin, indicating that the valence of anti-inflammatory action of the acylated derivatives is better than that of mangiferin (Chinese Journal of Experiment Traditional Medical Formulae Vol 18, No 24, page 185-189), The pharmacological experiments of epigallocatechin gallate octaacetate developed by multi-acylation modification of epigallocatechin gallate (the research group of Tak Hang Chan, Hong Kong Polytechnic University) showed that the derivative has improved stability and enhanced anti-cancer effectiveness (Bioorg & Medicinal Chemistry 12 (2004) 5587-5593). In summary, by esterification modification, the ester derivatives of drugs have improved liposolubility and show increased oil/water distribution coefficient and thus increased transmembrane permeability, leading to improved transmembrane absorption and bioavailability of drugs and ultimately enhanced drug efficacy. However, there is no such research on 20(R)-ginsenoside Rg3, therefore, we design and synthesize 20(R)-ginsenoside Rg3 polyacylated derivatives by alkali catalysis and conduct researches through pharmacological experiments.